Genetic code and its characteristics

Genetic code

  • It is a total genetic message encoded within the base sequence of the axons of the coding region of a gene.
  • It is the collection of codons that specify amino acids.

Codon

  • Every individual three-letter code word of genetic code is called a codon.
  • It consists of three consecutive bases, composed of A, T, G, and C at different combinations.
  • Each codon represents an amino acid.
  • There are altogether 64 codons

      1. Sense codon= 61

      2. None sense codon: 3

  • These are used to terminate protein synthesis.
  • They are:- UAG, UAA, UGA

Characteristics of genetic code

1. Universality

  • A codon representing a definite amino acid is universal and applicable to all organism
  • The same codon specifies the same amino acid in all species.

2.  Degeneracy/ Redundancy

  • For a given amino acid there is more than one codon( except for methionine and tryptophan which have only one codon)
  • Sense codon= 61
  • Total amino acid= 20

So, for one amino acid, there is more than one codon

3. Specificity/ unambiguous

  •  Forgiven codon there is only one amino acid.

4. Nonoverlapping

  • Consecutive triplet codons do not share any base and follow the strict sequence along with the reading frame of mRNA.

5. Commaless/ Nonpunctuated

  • Between the consecutive codons there are no extra bases to separate the codons.

Example:- abc def ghi